African citrus psyllid

Trioza erytreae

1. Identification

• Common name: African citrus psyllid
• Scientific name: Trioza erytreae Del Guercio
• Order: Hemiptera
• Family: Triozidae

2. Pest description

• Small sucking insect, 2–4 mm, yellowish-green to brownish in colour.
• Immobile, flattened nymphs, attached to the underside of the leaves.
• They produce sugary secretions and typical leaf deformations.
• The species is the vector agent of the bacterium Candidatus Liberibacter africanus, the causal agent of HLB (African greening) (a bacterial disease that causes irregular yellowing, deformations and progressive decline in citrus orchards).
• Priority quarantine pest in the European Union.

3. Main hosts

• Citrus (orange, mandarin, lemon, lime, grapefruit).
• Ornamental Rutaceae such as Murraya spp..
• Greater preference for young shoots and tender leaves.

4. Symptoms and damage

• Deformations and thickening of the leaves.
• Cavities and blisters on the upper side of the leaves.
• Abundant honeydew and development of sooty mould.
• Reduced vigour and production.
• High risk of introduction and spread of HLB, one of the most destructive citrus diseases.

5. Biological cycle

• Several generations per year in mild climates.
• Egg-laying on the margin of young leaves.
• Nymphs develop through 4–5 instars.
• Adults active throughout the year in coastal and humid regions.
• Populations increase rapidly in spring and autumn.

6. Monitoring

• Observation of deformations and blisters on the young leaves.
• Checking for nymphs on the underside of the leaves.
• Monitoring with yellow sticky traps.
• Intensive inspection in nurseries and new plantations.
• Recording of outbreaks and immediate communication to the phytosanitary authorities.

7. Management measures

• Cultural: removal of heavily attacked shoots and control of alternative host plants.
• Biological: conservation of natural parasitoids such as Tamarixia dryi when present.
• Integrated protection: continuous monitoring, interventions only when justified, judicious application of authorised insecticides and compliance with official containment and eradication measures.
• Official measures: compliance with DGAV and EU rules for quarantine pests, including restrictions on the movement of plants and plant material.

Bibliographic references

• EPPO Global Database – Trioza erytreae.
• CABI Invasive Species Compendium – T. erytreae.
• DGAV – Contingency Plan for Trioza erytreae (2015).
• DGAV – Phytosanitary updates on the African citrus psyllid (2019–2024).
• European Commission – Implementing Regulation (EU) 2019/2072 .
• Bové, J. (2006). Huanglongbing: a destructive, newly emerging citrus disease.